Implantable cardiac pacing devices or neurological stimulation devices comprise a metallic can holding the electronics. Electrical leads carry signals generated by the electronics to designated tissue or nerve sites so the signals stimulate the tissue or the nerve.
The electrical leads are connected to the metallic can during a surgical implant procedure. A connector assembly is formed on the metallic can for connecting the electronics to the leads. This assembly is encapsulated by an insulating and relatively fluid impermeable plastics material. The connector assembly is referred to as a header.
A range of different materials and their associated processing techniques are used to form headers. For example, epoxy materials are used as headers in certain applications. Epoxies have very long reaction time and can take hours to cure before they can be released from a mould.
As another example, hard grade polyurethane headers are used widely but they are exclusively used in the process of injection moulding. The process of injection moulding uses a high viscosity melt of a pre-formed polymer and this prevents good bonding to the electronic components and insulators. Therefore, the injection moulding happens as a separate step and the header is then mechanically or adhesively fixed on to the can.
For epoxies and polyurethanes, the manufacturing process of the header component is laborious, time consuming and ultimately unsatisfactory.
There is a need to provide an improved method of forming headers for implantable devices.